John Wetzel filled in at left tackle against the Panthers and is now the full-time starter following Jared Veldheer's torn triceps injury.

John Wetzel is far from invisible in the literal sense. He's 6-foot-7 and 328 pounds, the type of hulking presence that has people wondering if he's a professional athlete before he reveals his occupation.

"The first thing you notice about him," outside linebacker Alex Okafor said, "is he's a huge individual."

But for much of his NFL tenure, Wetzel has been in the shadows. He was an undrafted free agent out of Boston College in 2013 and bounced around practice squads before making the Cardinals' active roster this season.

He attained a level of prominence as a fill-in at guard against the 49ers and the Jets last month, but that pales in comparison to the spotlight he's about to enter.

A torn triceps landed left tackle Jared Veldheer on injured reserve, leaving a gaping hole at one of the most important positions in football. Wetzel has been summoned to fill it, in charge of Carson Palmer's all-important blindside for the rest of the season.

If he succeeds, Wetzel will be worth his hefty weight in gold. If he fails, the Cardinals' chances at turning around a 3-4-1 season will take a huge hit.

"There's a little bit of nervousness," Wetzel said. "It's new. But I'm really excited."

Wetzel earned a game ball for his performance against the 49ers -- playing guard despite not practicing there since training camp -- and replaced Veldheer adequately near the end of Sunday's game in Carolina. While he's done a nice job plugging holes in a leaky boat, now Wetzel has to take the wheel.

"He's been in games a couple times this year already, so he should be used to it," offensive coordinator Harold Goodwin said. "The only thing is, now he's definitely a full-time starter, not a part-time starter. That's got to be his mindset, and that's got to be the way he prepares."

The Cardinals have been spoiled since signing Veldheer before the 2014 season, penciling him in and worrying little about his ability to handle the pass rush. The year before he arrived, a combination of Levi Brown and Bradley Sowell at left tackle fared poorly, and the Cardinals hope Wetzel can be a more reliable stopgap.

Okafor faced Wetzel regularly in training camp, and was surprised with his dexterity and versatility for such a big guy. Okafor is not panicking about the Cardinals' situation at left tackle.

"This whole season, he's been the epitome of 'Next Man Up,'" Okafor said. "He's filled in wherever we've needed him. Now this left tackle job is going to be all his. More than anything, I'm just excited for him that he has the ability to go out there and showcase his skills on a consistent basis."

Wetzel isn't expected to be handled with kid gloves. Coach Bruce Arians runs an offense which includes deep drops and a lot of individual matchups on the outside of the line, which is not likely to change.

"We do have some protections where we give him a little bit of help, but for the most part he'll be by himself," Goodwin said.

It's a high-profile promotion, as even casual fans will be able to tell if he's getting regularly beat. For Wetzel, it is a welcome challenge. He toiled on practice squads for multiple seasons before this one, hoping to one day get a legitimate shot at playing time.

"I figured if I just kept doing what I was doing every week, somehow someone would see that I could play," he said. "Just work, get better and be ready when the opportunity comes."

It has arrived.

"He's not a kid that's lacking confidence," Goodwin said. "He's just got to go out and do what we coach him to do. Go out and put his hands on the defensive end and keep the quarterback clean, which we didn't do last week. I have all the trust in the world in him."